1. Field of the Invention
The present invention relates to a method for manufacturing an antibacterial synthetic fiber. More particularly, the present invention relates to an antibacterial synthetic fiber comprising a plant extract, and a method for manufacturing the same.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
A variety of attempts have been made to provide synthetic fibers with antibacterial activity. Prevalent among them is the inclusion of antibacterial inorganic substances into the synthetic fibers. Barleystone, jade, mica, and silver nanoparticles are representative of such inorganic substances. However, because they interfere with the manufacturing process of fibers, the inorganic substances are used in trace amounts which are not sufficient to guarantee the desired extent of antibacterial activity. Particularly, silver nanoparticles, known for their good antibacterial activity, additionally suffer from the drawback of having a negative influence on the light fastness of fibers following dyeing process, which is likely to cause a color change in the product.
In addition, conventional antibacterial synthetic fibers, although employing a trace amount of such an inorganic substance, are inferior in physical property to ordinary synthetic fibers.
In order to overcome these problems, extensive attention has been given to plant extracts or vegetable essential oils having antibacterial activity.
Exemplary are the disclosure of Korean Patent Nos. 10-0726409 and 10-0515808, which describe the direct coating and fixation of synthetic fibers with antibacterial plant extracts. The synthetic fibers coated with plant extracts do not persistently exhibit antibacterial activity because the extracts bleed out of the fibers upon washing.
The incorporation of plant extracts or vegetable essential oils into synthetic fibers arose as an alternative to coating, and methods therefor have been continuously studied.
As disclosed in Korean Patent Laid-Open Publication No. 2000-0058680 to the present inventors, efforts were made to elicit a deodorization effect by absorbing pyroligneous acid (wood vinegar) into porous mineral particles which were then used to prepare master batch chips. However, wood vinegar is viscous so that the mineral particles significantly aggregate when they are mixed with wood vinegar, resulting in plugging the filter of the mast batch facility. In addition, the aqueous liquid causes the degradation of the polymer, thus reducing the viscosity of the polymer. For these different reasons, the use of wood vinegar made it impossible to prepare master batch chips.
In the presence of water, mineral particles aggregate and once this aggregation of mineral particles has begun, it is fundamentally impossible to prevent. After a drying process, the aggregated mineral particles appear as solidified lumps which cannot be used in the manufacture of synthetic fibers. To be used, the aggregated mineral particles should be finely pulverized to the desired particle size, which may be achieved by repeating the milling process over time in, for example, a pin mill or a jet mill, followed by disintegration to prevent re-aggregation.
Although the mineral particles can be used after fine pulverization and disintegration, these processes are too expensive and increase the production cost.
Moreover, the fibers, even though obtained after the above-mentioned complex processes, still have the problem of having inferior physical properties because mineral substances act as a negative factor on physical properties as stated above.
Typical melting points for synthetic fibers are on the order of 200˜300° C. at which plant extracts or vegetable oils, if used in advance of melt spinning, may undergo evaporation, degradation and/or denaturation and thus cannot be incorporated into fibers or will not exhibit sufficient functionally even if incorporated.
In an effort to solve this problem, Korean Patent No. 10-0910241 teaches an electrospinning method by which fine fibers can be drawn at low temperatures from a solution of (a) at least one component selected from among plant extracts and vegetable essential oils and (b) at least one fiber-formable polymer in (c) a solvent.
In electrospinning, a solution is erupted from a nozzle by the electrical force existing between a collector and the nozzle and becomes a jet stream which is then dried into nanofibers as the solvent evaporates when it reaches an incomplete region. Electrospinning is considered to be a solution to most of the problems associated with conventional spinning methods. However, electrospun fibers show poor mechanical properties because they are not accompanied by the strength enhancement imparted by the molecular orientation of the polymer. For this reason, electrospun fibers are not used for clothes, but are limited to special industrial purposes.
In addition, electrospinning further suffers from the disadvantage of its process being unstable, increasing the production cost, and having a low production yield.
The method disclosed in US 2010/0221969 A1 is suggested as a solution to these problems. In the method, microcapsules containing vegetable essential oils are mixed with a polymeric material prior to spinning so as to provide the fibers with perfume. However, the microcapsules degrade the physical properties of the fibers. Particularly, the vegetable essential oils entrapped within the microcapsules may be released under the high pressure and temperature conditions that the polymeric materials are put through until they are melted and spun upon melt spinning. In this case, the released oils may have a negative influence on the physical properties of the polymeric materials, thus incurring unbeneficial results in the manufacturing processes.